Method and apparatus for rendering saline water potable



C. M. ASHLEY Jan. 15, 1963 METHOD AND APPARATUS FOR RENDERING SALINEWATER POTABLE Original Filed June 28, 1955 NVENTOR. f@ BY ite States3,073,131 METHOD AND APPARATUS FR RENDERING SALHNE WATER PQTABLE CarlyleM. Ashley, Fayetteville, NY., assiguor to Carrier Corporation, Syracuse,NSY., a corporation of Dela- Ware Original application June 28, 1955,Ser. No. 518,431. Di-

vided and this application Dec. 11, 1957, Ser. No.

2 Claims. (Cl. 62-58) This application is a division of my copendingapplication, Serial No. 518,431, filed June 28, 1955, and relates to amethod and apparatus for rendering saline Water potable and, moreparticularly, to a method and apparatus for converting sea water topotable water.

It is know that sea water may be purified by freezing. No commerciallysatisfactory system has heretofore been devised. Those systems whichhave been advanced either demand extravagant amounts of energy or elsepurify water inadequately. For example, prior centrifugal separationsystems had failed for even the great centrifugal forces used wereinsuicient to overcome the tenacity with which the brine clings to thenely divided ice. Washing systems were unsuccessful because of thetremendous amount of fresh water which they required. These difficultiesare more readily understandable when it is understood that the brine notonly clings to the surface of the ice but also remains in theinterstices between the ice crystals. This diicult situation is furtheraggravated by the need to reduce the impurity content of the water toless than 800 parts per million in order to render it potable.

The chief object of the present invention is to provide a method andapparatus for rendering saline water potable utilizing a freezingoperation which obviates the disadvantages present in systems heretoforeknown.

An object of the present invention is to provide apparatus forconverting a brine solution such as sea water to potable water which ishighly efficient and effective in operation and which utilizes afreezing operation to concentrate or remove potable water from thesolution.

A further object is to provide apparatus for forming and separatingpotable water from a brine solution such as sea Water in which freezingmeans are employed to form ice from the brine solution, the ice beingremoved from the solution, further cleaned to remove brine and melted toprovide potable Water.

A still further object is to provide a method of forming potable waterfrom a saline solution such as sea water. Other objects of the inventionVwill be readily perceived from the following description.

This invention relates to a method of rendering saline water potable inwhich the steps consist in forming ice from a saline solution such assea water thus creating a mixture of ice and sea water, separating theice from the mixture, and melting a portion of the ice to wash the brinefrom the surface and interstices of the ice. The word brine is employedherein to denote salt in solution and in a crystalline form.

This invention further relates to a system for rendering saline waterpotable which comprises means for forming ice from a saline solution,means for separating the ice and the brine, and means for melting aportion of the ice to wash the brine from the surface and interstices ofthe formed ice.

The attached drawing illustrates a preferred embodiment of theinvention.

Referring to the drawing there is shown a system which utilizes afreezing unit 402 and a separating and washing unit 403. In thisembodiment the freezing unit forms ice in suspension and the separatingand washing unit 2 washes the ice by partially melting the ice therebydraining brine from the surfaces and interstices of the ice.

The freezing unit 402 comprises a vertical cylindrical shell 404 havingan inner surface 405 in which is located a helical baffle 406 mounted ona filler shaft 407. The bale and filler shaft are concentrically locatedwithin the vertical cylindrical shell to form with surface 405 a helicalpassageway 408 within the shell. The cylindrical shell is refrigeratedby means of a jacket 409 placed about shell 404, forming with the wallof the shell a ooded evaporator. Liquid refrigerant is introduced intothe evaporator through inlet 411 and the gaseous refrigerant isdischarged from the evaporator through outlet 410.

The refrigerant for the evaporator is provided by a primaryrefrigeration system 440 and a secondary refrigeration system 441. Theprimary refrigeration system includes a compressor 442 and a condenser443. The condenser 443 comprises a horizontal cylindrical shell 444, atube bundle 445, a cooling water inlet 446 and a cooling water outlet447. The secondary refrigeration system includes a compressor 448 and acondenser 449 of any suitable type depending upon the characteristics ofthe cooling medium utilized.

Refrigerant passes through the outlet 410 to the T 450 and through line451 to the compressor 442 of the primary refrigeration system.Compressed refrigerant is forwarded through line 452 to co-ndenser 443,passing through the tube bundle 445 and being condensed therein bypotable water of a low temperature generated by the water purificationsystem. The condensed liquid refrigerant is withdrawn from the tubebundle 445 through line 453 to the T 454. Simultaneously, gaseousrefrigerant leaving the T 450 passes through line 455 to the compressor448 of the secondary refrigeration system, the compressed gaseousrefrigerant being forwarded through line 456 to the condenser 449. Thegaseous re,- frigerant is condensed in the condenser, liquid refrigerantpassing through line 458 and joins the line 453 at the T 454. Thecombined streams proceed through line 459 to the inlet 411 of theevaporator. A suitable valve 460 is located in the line 459 for thepurpose of controlling refrigerant flow to the evaporator.

Located at the upper portion of the freezing unit 402 is a sea waterinlet 412 through which sea water is introduced into the helicanpassageway 408. As the seal water passes through the passageway, it isrefrigerated forming a mixture of ice andy brine solution. As the brinesolution carrying the ice moves along the passageway, the ice convergestowards the center of the passageway while the brine solution remainsclose to the refrigerated inner surface 405. The ice and brine solutionso formed is discharged from the freezing unit through outlet 413located at the bottom of the cylindrical shell 404.

r111e separating and washing unit comprises a vertical cylindrical shell414 having an open upper end 415 and a lower closed end 416. Locatedintermediate with these ends is an ice and brine solution inlet 417. Themixture of ice and brine solution introduced into the cylindrical shellseparates due to forces of gravity, the heavier brine passingdownwardly. Simultaneously, the lighter ice rises and later emerges fromthe brine solution. Level of brine solution in the unit is maintainedabove ice and brine solution inlet 417 by a brine level control 420described hereafter.

Flush with the open end of the cylindrical shell 414 is located aslinger 421. Slinger 421 is driven by a motor 422. As ice emerges yfromthe brine solution and then from the cylindrical shell, it is urgedoutwardly by the slinger 421 which -throws the ice into a radial trough423 which extends concentrically around the open end of the cylindricalshell 414. The outer walls `of the trough l 3 are extended upwardly andover the trough and the open end of the shell thereby forming a hood424. Nozzles 425 are placed in the hood above the trough. Potable WaterYis sprayed through nozzles 425 to melt ice in trough 423. As the ice inthe trough melts, the potable' ing unit 492. Sea water is introducedinto the freezing unit/402through inlet 4&2. The sea water passes intoythe helical passageway 403 and as it passes through the passageway, thesea water is refrigerated as it passes in heat exchange relation withrefrigerant in the evaporator,` forming -a mixtureV of ice and brinesolution. As ice forms at the cylindrical shell (the refrigeratedsurface), the rotary motion of the brine solution as it passes throughthe helical passageway causes the formed ice: to converge or move towardthe center of the `passageway dueto its lesser density. Simultaneously,as the iceA moves. from the refrigerated shell surface it is replaced.by brine solution which has a greater density than the lighterV ice. Theice formed is suspended in the brine. solution and passes through thefreezing unit without caking for, as( the ice is formed, it isimmediately carried away from the refrigerated surface.

`The mixture of ice and brine solution so formed is withdrawn from` thefreezing unit through the Adischarge outletq413 and line 430 by a pump431. Pump 4.3i is operatively. connected tothe brine level control42.9." The mixtureY ofV ice and brine solution is forwarded by pump 4 31through line 432 to the combination separatingaudY washing unit., Themixture of ice and brine `solution' is discharged throughinlet 417 intothe cylindricalshell'414. As the mixtureof ice and brine solu'-tionlenters the shell there is a' natural separation in which theheavier brine falls to the bottom of the shell and is discharged throughoutlet did. The discharged brine solutionspasses through line 45S, andheat exchanger 42S and isadischarged Vfrom the system. The brinesolution isr ata very low temperature; hence, it tends to chill theincoming seawater passing through the heat exchangerto the freezingunit.

Simultaneously, as the brine solution falls down-Vwardly-in:the'cylindrical shell 414, the lighter ice passes upwardlytowardsfthe brine solution level 431.9. This brinesoltionlevelismaintained well below the open end415 of the vertical'shell. The'desired level is maintained by control 429 operatively connected to thepump 431 to regulate the amount of ice and brine solution pumped intothe vertical shell die..

As the mixture of iceand brine solution continues to be discharged intothe verticalshell, the ice, because of thebuoyant forces `cre-ated bythe heavier brine solution, tends'` to emerge above the brine solutionlevel. Preferably, temperature in hood 424 is so selected that partialmelting of the ice occurs. The water so formed creates a washing effectto washthe brine from the surface and interstices of the ice.

It isfunderstood that the ice which has emerged from the surface of thebrine solution is Vcontinually moving .upwardly until the ice contactsslinger 421. The rotary motion of the slinger moves the ice outwardlyaway from the open end of the shell. The ice falls into the trough 423.Simultaneously, warm Water is discharged through the nozzles 425 causingthe ice to melt and to drain through the outlet 426. The water formedfrom the melted ice passes through line 434, through the condenser 443where the refrigerant is cooled and is then forwarded by a pumptnotshown) through the heat exchanger 428 where it is again utilized tochill incoming A: sea water. The potable water is then collected at aplace of use or storage. Inline 434, there is a T 436, line 437 ybeingconnected thereto. Line 437 supplies water to the nozzles 42S of thewashing and melting unit. A control valve .38 is placed in line 437 toregulate the amount of water recirculated.

It should be noted that nozzles 425 have a twofold purpose. One functionis to provide potable Water to melt the ice collected in trough 422.;its -second function is to maintain temperature in the hood 424 at apoint such that ice formed in the shell will melt partially to providewashing of the ice as it emerges from the brine solution.

The present invention has been described with particular reference tothe formation ,of potablewater from sea water. It will be understood thestructure and method of the invention may be applied to theconcentration of fruit juices, purification of water, etc., with onlyslight adaptations in the present equipment and described methods.

While l have described a preferred embodiment of the invention, it willbe understood the invention is not limited thereto since it ,may beotherwise embodied within the scope of the lfollowing claims:

I claim: v

l. ln a system for rendering a saline solution potable, the combinationof a freezing vessel section; a separator vessel operatively connectedthereto; said freezing section including an inner cylindricalrefrigerated surface, a helical baffle, andV a concentric filler shaft,said baffle and shaft being arranged to provide a helical path withinsaid freezing section to impart centrifugal forces to the,

brine solution asV it passes through the freezing section whereby amixture of ice and brine solution is formed; said separator including avessel, a level control and a trough, said control maintaining a desiredbrine solution level in said vessel to permit ice to separate fromremaining brine solution by forces of buoyancy, said separator havingmeans for'partially melting said ice to wash solute fromthe surface andintersticesjofthe ice, 'and means for transferring the ice from saidseparator vessel to the trough.

, 2. ln a method for rendering a saline solution potable the steps whichconsistof. passing the saline solution into a helical passagewayenveloped by a refrigerated cylindrical surface, forming ice adjacentthe cylindrical surface, centrifugally displacing the less dense icewith saline solution adjacent the refrigerated surface, passing the iceinto the center of the stream passing through the helical passageway,passing the mixture of ice and salinesolution into a separation tank,settling the more dense concentrated saline solution in the bottom ofthe settling tank, passing, the less. dense ice and saline solution intothe upper 'portion of the settling tank, passing the ice above the levelof the saline solution in the settling tank, melting alportionV oftheice above the level of the saline solution to wash the brine from thesurface and interstices of the ice.

References Citedv inthe iileof this patent

2. IN A METHOD FOR RENDERING A SALINE SOLUTION POTABLE THE STEPS WHICHCONSIST OF PASSING THE SALINE SOLUTION INTO A HELICAL PASSAGEWAYENVELOPED BY A REFRIGERATED CYLINDRICAL SURFACE, FORMING ICE ADJACENTTHE CYLINDRICAL SURFACE, CENTRIFUGALLY DISPLACING THE LESS DENSE ICEWITH SALINE SOLUTION ADJACENT THE REFRIGERATED SURFACE, PASSING THE ICEINTO THE CENTER OF THE STREAM PASSING THROUGH THE HELICAL PASSAGEWAY,PASSING THE MIXTURE OF ICE AND SALINE SOLUTION INTO A SEPARATION TANK,SETTLING THE MORE DENSE CONCENTRATED SALINE SOLUTION IN THE BOTTOM OFTHE SETTLING TANK, PASSING THE LESS DENSE ICE AND SALINE SOLUTION INTOTHE UPPER PORTION OF THE SETTLING TANK, PASSING THE ICE ABOVE THE LEVELOF THE SALINE SOLUTION IN THE SETTLING TANK, MELTING A PORTION OF THEICE ABOVE THE LEVEL OF THE SALINE SOLUTION TO WASH THE BRINE FROM THESURFACE AND INTERSTRICES OF THE ICE.